Piezoelectric/electrostrictive device and method for manufacturing the same

ABSTRACT

A piezoelectric/electrostrictive device includes a stationary portion; a thin-plate portion supported by the stationary portion; and a piezoelectric/electrostrictive element including a plurality of electrodes and a plurality of piezoelectric/electrostrictive layers arranged alternatingly in layers. The piezoelectric/electrostrictive device is manufactured by the steps of forming a piezoelectric/electrostrictive laminate by alternatingly laminating laminar electrodes and piezoelectric/electrostrictive layers on a plane of a thin-plate member adapted to form the thin-plate portion, and cutting the thin-plate member and the piezoelectric/electrostrictive laminate. The cutting step is performed by advancing a wire member (wire saw) reciprocating in a direction parallel to the direction of lamination of the piezoelectric/electrostrictive laminate while holding the wire member substantially parallel to the direction of lamination. Thus, since the laminar electrodes are cut while being extended within corresponding layer planes, the degree of covering the end surfaces of the piezoelectric/electrostrictive layers decreases.

TECHNICAL FIELD

The present invention relates to a piezoelectric/electrostrictive deviceincluding a stationary portion, a thin-plate portion supported by thestationary portion, and a piezoelectric/electrostrictive elementincluding laminar electrodes and piezoelectric/electrostrictive layers,and to a method for manufacturing the same.

BACKGROUND ART

A piezoelectric/electrostrictive device of the above-mentioned type hasbeen developed as an actuator for precision working; as an actuator forcontrolling the position of a read and/or write element (head) forreading and/or writing optical information, magnetic information, orlike information; as a sensor for converting mechanical vibration to anelectrical signal; or as a like device.

FIG. 25 shows an example of such a piezoelectric/electrostrictivedevice. The piezoelectric/electrostrictive device includes a stationaryportion 100; thin-plate portions 110 supported by the stationary portion100; holding portions (movable portions) 120 provided at correspondingtip ends of the thin-plate portions 110 and adapted to hold an object;and piezoelectric/electrostrictive elements 130 formed at least oncorresponding planes of the thin-plate portions 110, eachpiezoelectric/electrostrictive element 130 including a plurality ofelectrodes and a plurality of piezoelectric/electrostrictive layersarranged alternatingly in layers. An electric field is generated betweenelectrodes of the piezoelectric/electrostrictive elements 130 to therebyextend and contract the piezoelectric/electrostrictive layers of thepiezoelectric/electrostrictive elements 130, whereby the thin-plateportions 110 are deformed. The deformation of the thin-plate portions110 causes displacement of the holding portions 120 (accordingly,displacement of the object held by the holding portions 120).

The piezoelectric/electrostrictive device of FIG. 25 is manufactured asfollows. First, as shown in FIG. 26, a plurality of ceramic green sheets(and/or a ceramic green sheet laminate) are prepared. As shown in FIG.27, these ceramic green sheets are laminated and then fired, therebyforming a ceramic laminate 200. As shown in FIG. 28,piezoelectric/electrostrictive laminates 210 each including a pluralityof electrodes and a plurality of piezoelectric/electrostrictive layersarranged alternatingly in layers are formed on the surface of theceramic laminate 200. The piezoelectric/electrostrictive laminates 210are cut along cutting lines C1 to C4 shown in FIG. 29, thereby yieldingthe piezoelectric/electrostrictive device.

However, as shown in FIG. 30, an enlarged fragmentary front view of thelateral end surface of the thin-plate portion 110 and thepiezoelectric/electrostrictive element 130, and in FIG. 31, an enlargedfragmentary, sectional view taken along line 1-1 of FIG. 30, whencutting is performed along the cutting lines C3 and C4 by use of a wiresaw WS, ductility of electrodes 131 of thepiezoelectric/electrostrictive element 130 causes the lateral endsurface (cut surface) of each of the electrodes 131 to extend onto thelateral end surface of a piezoelectric/electrostrictive layer 132located adjacently toward the direction of advancement of the wire sawWS (located adjacently downward in FIGS. 30 and 31). As a result, on thelateral end surface of the piezoelectric/electrostrictive element 130,the distance between the adjacent electrodes 131 is reduced.Furthermore, since the lateral end surface is exposed exteriorly, dustor the like tends to adhere thereto. As a result, it turned out that theadjacent electrodes are highly likely to short-circuit.

DISCLOSURE OF THE INVENTION

In view of the foregoing, an object of the present invention is toprovide a piezoelectric/electrostrictive device in which a sufficientdistance is maintained between electrodes as observed on the lateral endsurface (cut surface) of a piezoelectric/electrostrictive element, bydevising a method of cutting a piezoelectric/electrostrictive laminate,as well as to provide a method for manufacturing the same.

To achieve the above object, according to a feature of the presentinvention, a method for manufacturing a piezoelectric/electrostrictivedevice including a thin-plate portion, a stationary portion supportingthe thin-plate portion, and a piezoelectric/electrostrictive elementincluding a plurality of electrodes and a plurality ofpiezoelectric/electrostrictive layers arranged alternatingly in layerscomprises a step of forming a piezoelectric/electrostrictive laminate byalternatingly laminating laminar electrodes andpiezoelectric/electrostrictive layers on a plane of a thin-plate memberadapted to form the thin-plate portion; and a step of forming thethin-plate portion and the piezoelectric/electrostrictive element byadvancing a wire member reciprocating in a direction substantiallyparallel to the direction of lamination of thepiezoelectric/electrostrictive laminate while holding the wire membersubstantially parallel to the direction of lamination, so as to cut thethin-plate member and the piezoelectric/electrostrictive laminate.

According to another feature of the present invention, a method formanufacturing a piezoelectric/electrostrictive device including athin-plate portion, a stationary portion supporting the thin-plateportion, and a piezoelectric/electrostrictive element including aplurality of electrodes and a plurality ofpiezoelectric/electrostrictive layers arranged alternatingly in layerscomprises a step of forming a ceramic laminate by firing a ceramic greensheet laminate including a ceramic green sheet adapted to form thestationary portion, and a ceramic green sheet adapted to form thethin-plate portion; a step of forming a piezoelectric/electrostrictivelaminate at least on a surface of a portion of the ceramic laminatewhich is formed into the thin-plate portion, thepiezoelectric/electrostrictive laminate including laminar electrodes andpiezoelectric/electrostrictive layers arranged alternatingly in layers;and a step of forming the thin-plate portion and thepiezoelectric/electrostrictive element by advancing a wire memberreciprocating in a direction substantially parallel to the direction oflamination of the piezoelectric/electrostrictive laminate while holdingthe wire member substantially parallel to the direction of lamination,so as to cut the portion of the ceramic laminate which is formed intothe thin-plate portion, and the piezoelectric/electrostrictive laminate.

According to the method of the present invention, the thin-plate memberadapted to form the thin-plate portion, and thepiezoelectric/electrostrictive laminate adapted to form thepiezoelectric/electrostrictive element are cut by moving the wire memberin a direction parallel to a layer plane, the wire member reciprocatingin a direction substantially parallel to the direction of lamination ofthe piezoelectric/electrostrictive laminate (i.e., in a directionsubstantially perpendicular to the layer plane) while being heldsubstantially parallel to the direction of lamination. Accordingly,force that is applied from the wire member to each of the electrodes inassociation with cutting and that acts on the electrode in such a manneras to extend the electrode is directed mainly in the layer plane of theelectrode. Also, force that is generated in association with thereciprocating movement of the wire member during cutting and that actson the electrode in such a manner as to extend the electrode is directedsubstantially evenly toward the lateral end surfaces of twopiezoelectric/electrostrictive layers between which the electrode issandwiched. As a result, the present invention provides thepiezoelectric/electrostrictive device in which, on an exteriorly exposedlateral end surface (cut surface) of the piezoelectric/electrostrictiveelement, a relatively large distance is maintained between adjacentelectrodes.

In other words, by use of the above-mentioned manufacturing method, thepresent invention can provide a piezoelectric/electrostrictive devicecomprising a thin-plate portion; a stationary portion supporting thethin-plate portion; and a piezoelectric/electrostrictive element formedat least on a plane of the thin-plate portion, thepiezoelectric/electrostrictive element including a plurality ofelectrodes and a plurality of piezoelectric/electrostrictive layersarranged alternatingly in layers, and having an exteriorly exposedlateral end surface including lateral end surfaces of the plurality ofelectrodes and lateral end surfaces of the plurality ofpiezoelectric/electrostrictive layers; wherein a portion of eachelectrode which portion forms the corresponding lateral end surfaceextends onto both of the lateral end surfaces of thepiezoelectric/electrostrictive layers between which the electrode issandwiched, in such a manner as to partially cover the lateral endsurfaces of the piezoelectric/electrostrictive layers.

The piezoelectric/electrostrictive device of the present invention issuch that, on the lateral end surface of thepiezoelectric/electrostrictive element, the length (L2) of a portion ofeach electrode which forms the corresponding lateral end surface of theelectrode as measured in the direction of lamination of thepiezoelectric/electrostrictive layers and the electrode is smaller thanfive times the length (L1) of the electrode as measured in the directionof lamination and on an imaginary plane (HPL) defined by the lateral endsurfaces of the piezoelectric/electrostrictive layers.

Also, the piezoelectric/electrostrictive device of the present inventionis such that a ratio of L3/L1 satisfies 0<L3/L1<2 (i.e., L3/L1 isgreater than 0 and smaller than 2), where L3 is the length of the longerof parts of a lateral-end-surface-forming portion of each electrodewhich portion forms the corresponding lateral end surface of theelectrode, the parts of the portion covering the corresponding lateralend surfaces of the piezoelectric/electrostrictive layers between whichthe electrode is sandwiched, the length being measured in the directionof lamination of the piezoelectric/electrostrictive layers and theelectrode; and L1 is the thickness, as measured in the direction oflamination, of the lateral-end-surface-forming portion of the electrodeafter removal of the parts covering the corresponding lateral endsurfaces of the piezoelectric/electrostrictive layers from thelateral-end-surface-forming portion of the electrode.

The piezoelectric/electrostrictive device in which the length (L2) of aportion of each electrode which forms the corresponding lateral endsurface of the electrode is smaller than five times the length (L1) ofthe electrode as measured in the direction of lamination and on theimaginary plane (HPL) defined by the lateral end surfaces of thepiezoelectric/electrostrictive layers, or thepiezoelectric/electrostrictive device in which the ratio L3/L1 satisfies0<L3/L1<2, is highly unsusceptible to a failure to exhibit sufficientinsulating performance at the stage of completion of manufacture thereofand is highly unlikely to impair its insulating performance in thecourse of use.

The above-mentioned manufacturing method of the present inventionprovides a piezoelectric/electrostrictive device comprising a thin-plateportion; a stationary portion supporting the thin-plate portion; and apiezoelectric/electrostrictive element formed at least on a plane of thethin-plate portion, including a plurality of electrodes and a pluralityof piezoelectric/electrostrictive layers arranged alternatingly inlayers, having an exteriorly exposed lateral end surface includinglateral end surfaces of the plurality of electrodes and lateral endsurfaces of the plurality of piezoelectric/electrostrictive layers;wherein the exteriorly exposed lateral end surface of thepiezoelectric/electrostrictive element is a surface formed by cutting alaminate of the electrodes and the piezoelectric/electrostrictivelayers, in a direction substantially perpendicular to the direction oflamination of the laminate in a plane parallel to the direction oflamination.

According to a further feature of the present invention, a method formanufacturing a piezoelectric/electrostrictive device including athin-plate portion and a piezoelectric/electrostrictive elementincluding a laminar first electrode formed on a plane of the thin-plateportion, a piezoelectric/electrostrictive layer formed on the firstelectrode, and a laminar second electrode formed on thepiezoelectric/electrostrictive layer comprises a step of forming alaminate adapted to form the piezoelectric/electrostrictive element, ona plane of a thin-plate member adapted to form the thin-plate portion;and a step of forming the thin-plate portion and thepiezoelectric/electrostrictive element by advancing a wire memberreciprocating in a direction substantially parallel to the direction oflamination of the laminate while holding the wire member substantiallyparallel to the direction of lamination, so as to cut the thin-platemember and the laminate.

Also, in this case, the thin-plate member adapted to form the thin-plateportion, and the laminate adapted to form thepiezoelectric/electrostrictive element including the first and secondelectrodes and the piezoelectric/electrostrictive layer sandwichedbetween the first and second electrodes are cut by moving the wiremember in a direction parallel to a layer plane, the wire memberreciprocating in a direction substantially parallel to the direction oflamination of the piezoelectric/electrostrictive laminate (i.e., in adirection substantially perpendicular to the layer plane) while beingheld substantially parallel to the direction of lamination. Accordingly,force that is applied from the wire member to the first and secondelectrodes in association with cutting and that acts on the first andsecond electrodes in such a manner as to extend the electrodes isdirected mainly in the layer planes of the first and second electrodes.As a result, the present invention provides thepiezoelectric/electrostrictive device in which, on an exteriorly exposedlateral end surface (cut surface) of the piezoelectric/electrostrictiveelement, a relatively large distance is maintained between the first andsecond electrodes. In other words, the present invention provides thepiezoelectric/electrostrictive device in which a portion of the firstelectrode which portion forms the lateral end surface thereof extendsonto the lateral end surface of the thin-plate portion and onto thelateral end surface of the piezoelectric/electrostrictive layer in sucha manner as to partially cover the lateral end surface of the thin-plateportion and the lateral end surface of thepiezoelectric/electrostrictive layer, and in which a relatively largedistance is maintained between the first and second electrodes asobserved on the lateral end surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a piezoelectric/electrostrictive deviceaccording to an embodiment of the present invention;

FIG. 2 is a perspective view of the piezoelectric/electrostrictivedevice of FIG. 1 and an object held by thepiezoelectric/electrostrictive device;

FIG. 3 is an enlarged fragmental front view of thepiezoelectric/electrostrictive device of FIG. 1;

FIG. 4 is a perspective view of a variant of thepiezoelectric/electrostrictive device of FIG. 1;

FIG. 5 is a perspective view of ceramic green sheets to be laminated ina first method for manufacturing a piezoelectric/electrostrictive deviceaccording to the present invention;

FIG. 6 is a perspective view of a ceramic green sheet laminate formed bylaminating and compression-bonding the ceramic green sheets of FIG. 5;

FIG. 7 is a perspective view of a ceramic laminate formed bymonolithically firing the ceramic green sheet laminate of FIG. 6;

FIG. 8 is a perspective view of the ceramic laminate of FIG. 7 on whichpiezoelectric/electrostrictive laminates are formed;

FIG. 9 is a view showing a cutting step for cutting the ceramic laminateand the piezoelectric/electrostrictive laminates shown in FIG. 8;

FIG. 10 is a fragmentary front view of a lateral end surface (cutsurface) of the piezoelectric/electrostrictive element and thethin-plate portion shown in FIG. 1;

FIG. 11 is a fragmentary, sectional view taken along line 2-2 of FIG. 10and showing the piezoelectric/electrostrictive element and thethin-plate portion;

FIG. 12 is an enlarged fragmentary view of FIG. 11;

FIG. 13 is an enlarged fragmentary front view of a lateral end surface(cut surface) of a piezoelectric/electrostrictive element manufacturedby a method other than that of the present invention;

FIG. 14 is a perspective view of ceramic green sheets to be laminated ina second method for manufacturing a piezoelectric/electrostrictivedevice according to the present invention;

FIG. 15 is a perspective view of a ceramic green sheet laminate formedby laminating and compression-bonding the ceramic green sheets of FIG.14;

FIG. 16 is a perspective view of a ceramic laminate formed bymonolithically firing the ceramic green sheet laminate of FIG. 15;

FIG. 17 is a perspective view of the ceramic laminate of FIG. 16 onwhich piezoelectric/electrostrictive laminates are formed;

FIG. 18 is a view showing a cutting step for cutting the ceramiclaminate and the piezoelectric/electrostrictive laminates shown in FIG.17;

FIG. 19 is an enlarged fragmentary front view of a ceramic green sheetcorresponding to the ceramic green sheet shown in FIG. 14;

FIG. 20 is an enlarged fragmentary front view of another example of aceramic green sheet corresponding to the ceramic green sheet shown inFIG. 14;

FIG. 21 is an enlarged fragmentary front view of still another exampleof a ceramic green sheet corresponding to the ceramic green sheet shownin FIG. 14;

FIG. 22 is a perspective view of another variant of thepiezoelectric/electrostrictive device of FIG. 1;

FIG. 23 is a view showing another example in which an object is held onthe piezoelectric/electrostrictive device according to each of theembodiments;

FIG. 24 is a perspective view of still another variant of thepiezoelectric/electrostrictive device of FIG. 1;

FIG. 25 is a perspective view of a conventionalpiezoelectric/electrostrictive device;

FIG. 26 is a perspective view of ceramic green sheets to be laminated inthe process of manufacturing the piezoelectric/electrostrictive deviceof FIG. 25;

FIG. 27 is a perspective view of a ceramic laminate formed bymonolithically firing a ceramic green sheet laminate formed bylaminating and compression-bonding the ceramic green sheets of FIG. 26;

FIG. 28 is a perspective view of the ceramic laminate of FIG. 27 onwhich piezoelectric/electrostrictive laminates are formed;

FIG. 29 is a view showing a cutting step for cutting the ceramiclaminate and the piezoelectric/electrostrictive laminates shown in FIG.28 in a manufacturing method other than that of the present invention;

FIG. 30 is a fragmentary front view of a lateral end surface (cutsurface) of the piezoelectric/electrostrictive element and thethin-plate portion shown in FIG. 25;

FIG. 31 is a fragmentary, sectional view taken along line 1-1 of FIG. 30and showing the piezoelectric/electrostrictive element and thethin-plate portion; and

FIG. 32 is a view showing a cutting step for cutting the ceramiclaminates and the piezoelectric/electrostrictive laminates shown in FIG.8.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of a piezoelectric/electrostrictive device according tothe present invention will next be described with reference to thedrawings. As shown in the perspective view of FIG. 1, apiezoelectric/electrostrictive device 10 according to the presentembodiment includes a stationary portion 11 in the shape of arectangular parallelepiped; a pair of mutually facing thin-plateportions 12, which are supported by the stationary portion 11 in astanding condition; two holding portions (movable portions) 13 providedat corresponding tip ends of the thin-plate portions 12 and having athickness greater than that of the thin-plate portions 12; and twopiezoelectric/electrostrictive elements 14 formed at least oncorresponding outer planes of the thin-plate portions 12 and includinglaminar electrodes and piezoelectric/electrostrictive layers arrangedalternatingly in layers. The general configurations of these portionsare disclosed in, for example, Japanese Patent Application Laid-Open(kokai) No. 2001-320103.

As shown in FIG. 2, the piezoelectric/electrostrictive device 10 isused, for example, as an actuator in which an object S is held betweenthe paired holding portions 13, and force generated by thepiezoelectric/electrostrictive elements 14 causes the thin-plateportions 12 to be deformed to thereby displace the holding portions 13for controlling the position of the object S. The object S is a magnetichead, an optical head, a sensitivity-adjusting weight for use in asensor, or the like.

A portion (also generically called a “substrate portion”) that thestationary portion 11, the thin-plate portions 12, and the holdingportions 13 constitute is a ceramic laminate, which is formed by firinga laminate of ceramic green sheets as will be described later in detail.Such a monolithic ceramic element does not use an adhesive for joiningits portions and is thus almost free from a change in state with time,thereby providing a highly reliable joint and having advantage in termsof attainment of rigidity. The ceramic laminate can be readilymanufactured by a ceramic green sheet lamination process, which will bedescribed later.

The entire substrate portion may be formed from ceramic or metal or mayassume a hybrid structure in which ceramic and metal are used incombination. Also, the substrate portion may be configured such thatceramic pieces are bonded together by means of an adhesive, such as anorganic resin or glass, or such that metallic pieces are joined togetherby means of brazing, soldering, eutectic bonding, diffusion joining,welding, or the like.

As shown in the enlarged view of FIG. 3, thepiezoelectric/electrostrictive element 14 is formed on an outer wallsurface (outer plane) formed by the stationary portion 11 (a portion ofthe stationary portion) and the thin-plate portion 12 (a portion of thethin-plate portion), includes a plurality of laminar electrodes and aplurality of piezoelectric/electrostrictive layers, and assumes the formof a laminate in which the laminar electrodes and thepiezoelectric/electrostrictive layers are arranged alternatingly inlayers. The electrode layers and the piezoelectric/electrostrictivelayers are parallel to the plane of the thin-plate portion 12. Morespecifically, the piezoelectric/electrostrictive element 14 is alaminate in which an electrode 14 a 1, a piezoelectric/electrostrictivelayer 14 b 1, an electrode 14 a 2, a piezoelectric/electrostrictivelayer 14 b 2, an electrode 14 a 3, a piezoelectric/electrostrictivelayer 14 b 3, an electrode 14 a 4, a piezoelectric/electrostrictivelayer 14 b 4, and an electrode 14 a 5 are laminated in that order on theouter plane of the thin-plate portion 12. The electrodes 14 a 1, 14 a 3,and 14 a 5 are electrically connected together and are insulated fromthe electrically connected electrodes 14 a 2 and 14 a 4. In other words,the electrically connected electrodes 14 a 1, 14 a 3, and 14 a 5 and theelectrically connected electrodes 14 a 2 and 14 a 4 are arranged in ashape resembling the teeth of a comb.

The piezoelectric/electrostrictive element 14 is formed integrally withthe substrate portion by a film formation process, which will bedescribed later. Alternatively, the piezoelectric/electrostrictiveelement 14 may be manufactured separately from the substrate portion,followed by a process of joining the piezoelectric/electrostrictiveelement 14 to the substrate portion by use of an adhesive, such as anorganic resin, or by means of glass, brazing, soldering, eutecticbonding, or the like.

The present embodiment shows a multilayered structure including fiveelectrode layers; however, the number of layers is not particularlylimited. Generally, as the number of layers increases, a force (driveforce) for deforming the thin-plate portions 12 increase, but powerconsumption also increases. Accordingly, the number of layers may beselected according to, for example, application and the state of use.

A supplementary description of component elements of thepiezoelectric/electrostrictive device 10 will next be given below.

The holding portions 13 operate on the basis of displacement of thethin-plate portions 12. Various members are attached to the holdingportions 13 according to applications of thepiezoelectric/electrostrictive device 10. For example, when thepiezoelectric/electrostrictive device 10 is used as an element(displacing element) for displacing an object, particularly when thepiezoelectric/electrostrictive 10 is used for positioning or suppressingwringing of a magnetic head of a hard disk drive, a slider having amagnetic head, a magnetic head, a suspension having a slider, or a likemember (i.e., a member required to be positioned) may be attached. Also,the shield of an optical shutter or the like may be attached.

As mentioned previously, the stationary portion 11 is adapted to supportthe thin-plate portions 12 and the holding portions 13. When thepiezoelectric/electrostrictive device 10 is used for, for example,positioning the magnetic head of a hard disk drive, the stationaryportion 11 is fixedly attached to a carriage arm attached to a VCM(voice coil motor), to a fixture plate attached to the carriage arm, toa suspension, or to a like member. In some cases, unillustratedterminals and other members for driving thepiezoelectric/electrostrictive elements 14 may be arranged on thestationary portion 11. The terminals may have a width similar to that ofthe electrodes or may be narrower or partially narrower than theelectrodes.

No particular limitations are imposed on a material for the holdingportions 13 and the stationary portion 11, so long as the holdingportions 13 and the stationary portion 11 can have rigidity. Generally,use of a ceramic as the material is preferred, since a ceramic greensheet lamination process, which will be described later, can be applied.More specifically, examples of the material include a material thatcontains, as a main component, zirconia (such as stabilized zirconia orpartially stabilized zirconia), alumina, silicon nitride, aluminumnitride, or titanium oxide; and a material that contains a mixture ofthem as a main component. A material that contains zirconia,particularly stabilized zirconia or partially stabilized zirconia, as amain component is preferred for the piezoelectric/electrostrictivedevice 10, since mechanical strength and toughness are high. When ametallic material is to be used for manufacturing the holding portions13 and the stationary portion 11, stainless steel, nickel, or the likeis preferred as the metallic material.

As mentioned previously, the thin-plate portions 12 are driven by thepiezoelectric/electrostrictive elements 14. The thin-plate portions 12are thin-plate-like members having flexibility and have a function forconverting extension/contraction displacement of thepiezoelectric/electrostrictive elements 14 disposed on their surfaces tobending displacement and transmitting the bending displacement to thecorresponding holding portions 13. Accordingly, no particularlimitations are imposed on the shape of and a material for thethin-plate portions 12, so long as the thin-plate portions 12 areflexible and have such mechanical strength as not to be broken frombending deformation; and the shape and material are selected in view of,for example, response and operability of the holding portions 13.

The thickness Dd (see FIG. 1) of the thin-plate portion 12 is preferablyabout 2 μm to 100 μm; and the total thickness of the thin-plate portion12 and the piezoelectric/electrostrictive element 14 is preferably 7 μmto 500 μm. The thickness of each of the electrodes 14 a 1 to 14 a 5 ispreferably 0.1 μm to 50 μm; and the thickness of each of thepiezoelectric/electrostrictive layers 14 b 1 to 14 b 4 is preferably 3μm to 300 μm.

Preferably, as in the case of the holding portions 13 and the stationaryportion 11, a ceramic is used to form the thin-plate portions 12. Amongceramics, zirconia, particularly a material that contains stabilizedzirconia as a main component, or a material that contains partiallystabilized zirconia as a main component, is more preferred because ofhigh mechanical strength exhibited even in thin-walled application, hightoughness, and low reactivity with the electrode material of theelectrodes 14 a 1 and the piezoelectric/electrostrictive layers 14 b 1,which constitute the piezoelectric/electrostrictive element 14.

The thin-plate portions 12 can also be formed from a metallic materialthat has flexibility and allows bending deformation. Among preferredmetallic materials for the thin-plate portions 12, examples of ferrousmaterials include stainless steels and spring steels, and examples ofnonferrous materials include beryllium copper, phosphor bronze, nickel,and nickel—iron alloys.

Preferably, stabilized zirconia or partially stabilized zirconia to beused in the piezoelectric/electrostrictive device 10 is stabilized orpartially stabilized in the following manner. At least one or more thanone compound selected from the group consisting of yttrium oxide,ytterbium oxide, cerium oxide, calcium oxide, and magnesium oxide isadded to zirconia to thereby stabilize or partially stabilize thezirconia.

Each of the compounds is added in the following amount: in the case ofyttrium oxide or ytterbium oxide, 1 mol % to 30 mol %, preferably 1.5mol % to 10 mol %; in the case of cerium oxide, 6 mol % to 50 mol %,preferably 8 mol % to 20 mol %; and in the case of calcium oxide ormagnesium oxide, 5 mol % to 40 mol %, preferably 5 mol % to 20 mol %.Particularly, use of yttrium oxide as a stabilizer is preferred. In thiscase, preferably, yttrium oxide is added in an amount of 1.5 mol % to 10mol % (more preferably, 2 mol % to 4 mol % when mechanical strength isregarded as important, or 5 mol % to 7 mol % when endurance reliabilityis regarded as important).

Alumina, silica, transition metal oxide, or the like can be added as asintering aid or the like in an amount of 0.05 wt % to 20 wt %. In thecase where the piezoelectric/electrostrictive elements 14 are formed bymeans of film formation and monolithic firing, addition of alumina,magnesia, transition metal oxide, or the like is preferred.

In the case where at least one of the stationary portion 11, thethin-plate portion 12, and the holding portion 13 is formed from aceramic, in order to obtain a ceramic having a high mechanical strengthand stable crystal phase, the average crystal grain size of zirconia ispreferably set to 0.05 μm to 3 μm, more preferably 0.05 μm to 1 μm. Asmentioned previously, the thin-plate portions 12 may be formed from aceramic similar to (but different from) that used to form the holdingportions 13 and the stationary portion 11. However, preferably, thethin-plate portions 12 are formed from a material substantiallyidentical with that of the holding portions 13 and the stationaryportion 11 in view of enhancement of the reliability of joint portions,enhancement of the strength of the piezoelectric/electrostrictive device10, and simplification of a procedure for manufacturing thepiezoelectric/electrostrictive device 10.

A piezoelectric/electrostrictive device can use apiezoelectric/electrostrictive element of a unimorph type, a bimorphtype, or the like. However, the unimorph type, in which the thin-plateportions 12 and corresponding piezoelectric/electrostrictive elementsare combined together, is advantageous in terms of stability ofdisplacement quantity, a reduction in weight, and easy design foravoiding occurrence of opposite orientations between stress generated inthe piezoelectric/electrostrictive element and strain associated withdeformation of the piezoelectric/electrostrictive device. Therefore, theunimorph type is suited for the piezoelectric/electrostrictive device10.

When, as shown in FIG. 1, the piezoelectric/electrostrictive elements 14are formed in such a manner that one end of each of thepiezoelectric/electrostrictive elements 14 is located on the stationaryportion 11 (or the corresponding holding portion 13), whereas the otherend is located on the plane of the corresponding thin-plate portion 12,the thin-plate portions 12 can be driven to a greater extent.

Preferably, the piezoelectric/electrostrictive layers 14 b 1 to 14 b 4are formed from a piezoelectric ceramic. Alternatively, thepiezoelectric/electrostrictive layers 14 b 1 to 14 b 4 may be formedfrom an electrostrictive ceramic, a ferroelectric ceramic, or anantiferroelectric ceramic. In the case where, in thepiezoelectric/electrostrictive device 10, the linearity between thedisplacement quantity of the holding portions 13 and a drive voltage (oroutput voltage) is regarded as important, preferably, thepiezoelectric/electrostrictive layers 14 b 1 to 14 b 4 are formed from amaterial having low strain hysteresis. Therefore, preferably, thepiezoelectric/electrostrictive layers 14 b 1 to 14 b 4 are formed from amaterial whose coercive electric field is 10 kV/mm or less.

A specific material for the piezoelectric/electrostrictive layers 14 b 1to 14 b 4 is a ceramic that contains, singly or in combination, leadzirconate, lead titanate, magnesium lead niobate, nickel lead niobate,zinc lead niobate, manganese lead niobate, antimony lead stannate,manganese lead tungstate, cobalt lead niobate, barium titanate, sodiumbismuth titanate, potassium sodium niobate, strontium bismuth tantalate,and the like.

Particularly, a material that contains a predominant amount of leadzirconate, lead titanate, and magnesium lead niobate, or a material thatcontains a predominant amount of sodium bismuth titanate is preferred asa material for the piezoelectric/electrostrictive layers 14 b 1 to 14 b4, in view of high electromechanical coupling coefficient, highpiezoelectric constant, low reactivity with the thin-plate (ceramic)portion 12 during sintering of the piezoelectric/electrostrictive layers14 b 1 to 14 b 4, and obtainment of consistent composition.

Furthermore, there can be used, as a material for thepiezoelectric/electrostrictive layers 14 b 1 to 14 b 4, a ceramic thatcontains an oxide of, for example, lanthanum, calcium, strontium,molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, cerium,cadmium, chromium, cobalt, antimony, iron, yttrium, tantalum, lithium,bismuth, or tin. In this case, incorporation of lanthanum or strontiuminto lead zirconate, lead titanate, or magnesium lead niobate, which isa predominant component, may yield in some cases such an advantage thatcoercive electric field and a piezoelectric characteristic becomeadjustable.

Notably, addition of a material prone to vitrify, such as silica, to amaterial for the piezoelectric/electrostrictive layers 14 b 1 to 14 b 4is desirably avoided. This is because silica or a like material is proneto react with a piezoelectric/electrostrictive material during thermaltreatment of the piezoelectric/electrostrictive layers 14 b 1 to 14 b 4;as a result, the composition of the piezoelectric/electrostrictivematerial varies with a resultant deterioration in the piezoelectricproperty.

Meanwhile, preferably, the electrodes 14 a 1 to 14 a 5 of thepiezoelectric/electrostrictive elements 14 are formed from a metal thatis solid at room temperature and has excellent electrical conductivity.Examples of the metal include aluminum, titanium, chromium, iron,cobalt, nickel, copper, zinc, niobium, molybdenum, ruthenium, palladium,rhodium, silver, tin, tantalum, tungsten, iridium, platinum, gold, lead,and an alloy of these metals. Furthermore, an electrode material can bea cermet material prepared by dispersing in any of the above metals amaterial identical with that of the piezoelectric/electrostrictivelayers 14 b 1 to 14 b 4 or that of the thin-plate portions 12.

Selection of an electrode material for use in thepiezoelectric/electrostrictive element 14 depends on a method of formingthe piezoelectric/electrostrictive layers 14 b 1 to 14 b 4. For example,in the case where the electrode 14 a 1 is formed on the thin-plateportion 12, and then the piezoelectric/electrostrictive layer 14 b 1 isformed on the electrode 14 a 1 by means of firing, the electrode 14 a 1must be formed of a high-melting-point metal, such as platinum,palladium, a platinum-palladium alloy, or a silver-palladium alloy, thatremains intact even when exposed to a firing temperature of thepiezoelectric/electrostrictive layer 14 b 1. This also applies to otherelectrodes (electrodes 14 a 2 to 14 a 4) whose formation is followed byfiring of corresponding piezoelectric/electrostrictive layers.

By contrast, in the case of the outermost electrode 14 a 5 to be formedon the piezoelectric/electrostrictive layer 14 b 4, the formation of theelectrode 14 a 5 is not followed by firing of apiezoelectric/electrostrictive layer. Thus, the electrode 14 a 5 can beformed from a low-melting-point metal, such as aluminum, gold, orsilver.

Since the laminar electrodes 14 a 1 to 14 a 5 possibly cause a reductionin displacement of the piezoelectric/electrostrictive element 14, eachof the electrode layers is desirably thin. Particularly, the electrode14 a 5, which is formed after the piezoelectric/electrostrictive layer14 b 4 is fired, is formed preferably from an organic metal paste, whichenables the formation of a dense, very thin film after firing. Examplesof the paste include a gold resinate paste, a platinum resinate paste,and a silver resinate paste.

In the piezoelectric/electrostrictive device 10 of FIG. 1, the holdingportions 13, which are formed integrally with the corresponding tip endportions of the thin-plate portions 12, have a thickness greater thanthe thickness Dd of the thin-plate portions 12. However, as shown inFIG. 4, the holding portions 13 may have a thickness substantially equalto that of the thin-plate portions 12. As a result, an object to be heldbetween the holding portions 13 can have a size corresponding to thedistance between the thin-plate portions 12. In this case, regions wherean adhesive is applied in order to hold the object virtually serves asthe corresponding holding portions 13. Furthermore, in this case, aprojection for specifying the region where an adhesive is applied may beprovided. Desirably, such a projection is formed from the same materialas that of the thin-plate portion 12 and integrally with the thin-plateportion 12 by means of monolithic sintering or monolithic molding.

The above-mentioned piezoelectric/electrostrictive device 10 can also beused as an ultrasonic sensor, an acceleration sensor, anangular-velocity sensor, an impact sensor, a mass sensor, or a likesensor. In application to such a sensor, thepiezoelectric/electrostrictive device 10 is advantageous in that sensorsensitivity can be readily adjusted by means of appropriately adjustingthe size of an object to be held between the opposed holding portions 13or between the opposed thin-plate portions 12.

Next, a method for manufacturing the above-mentionedpiezoelectric/electrostrictive device 10 will be described. Preferably,a substrate portion (which excludes the piezoelectric/electrostrictiveelements 14; i.e., which includes the stationary portion 11, thethin-plate portions 12, and the holding portions 13) of thepiezoelectric/electrostrictive device 10 is manufactured by a ceramicgreen sheet lamination process. Meanwhile, preferably, thepiezoelectric/electrostrictive elements 14 are manufactured by a filmformation process, which is adapted to form a thin film, a thick film,and a like film.

A ceramic green sheet lamination process allows integral formation ofmembers of the substrate portion of the piezoelectric/electrostrictivedevice 10. Thus, the employment of a ceramic green sheet laminationprocess allows a joint portion between members to be almost free from achange in state with time, thereby enhancing the reliability of jointportions and securing rigidity. In the case where the substrate portionis formed by laminating metallic plates, the employment of a diffusionjoining process allows a joint portion between members to be almost freefrom a change in state with time, thereby securing the reliability ofjoint portions, and rigidity.

In the piezoelectric/electrostrictive device 10 of FIG. 1 according tothe present embodiment, boundary portions (joint portions) between thethin-plate portions 12 and the stationary portion 11, and boundaryportions (joint portions) between the thin-plate portions 12 and thecorresponding holding portions 13 serve as fulcrum points formanifestation of displacement. Therefore, the reliability of the jointportions is an important factor that determines the characteristics ofthe piezoelectric/electrostrictive device 10.

A manufacturing method to be described below features high productivityand excellent formability and thus can yield thepiezoelectric/electrostrictive devices 10 having a predetermined shapein a short period of time with good reproducibility.

A first method for manufacturing the piezoelectric/electrostrictivedevice 10 according to the present embodiment will next be described. Inthe following description, a laminate obtained by laminating a pluralityof ceramic green sheets is defined as a ceramic green sheet laminate 22(see FIG. 6); and a monolithic body obtained by firing the ceramic greensheet laminate 22 is defined as a ceramic laminate 23 (see FIG. 7).

The manufacturing method is embodied desirably as follows: a singlesheet equivalent to a plurality of ceramic laminates of FIG. 7 arrangedlengthwise and crosswise is prepared; a laminate corresponding to aplurality of laminates 24 (see FIG. 8), which are formed into thepiezoelectric/electrostrictive elements 14, is formed continuously onthe surfaces of the sheet in predetermined regions; and the sheet iscut, whereby a plurality of piezoelectric/electrostrictive devices 10are manufactured in the same process. Furthermore, desirably, two ormore piezoelectric/electrostrictive devices 10 are yielded inassociation with a single window (including Wd1 and the like shown inFIG. 5). It should be noted that in order to simplify description, thefollowing description discusses a method for obtaining a singlepiezoelectric/electrostrictive device 10 from a ceramic laminate bycutting the ceramic laminate.

First, a binder, a solvent, a dispersant, a plasticizer, and the likeare mixed with a ceramic powder of zirconia or the like, therebypreparing a slurry. The slurry is defoamed. By use of the defoamedslurry, a rectangular ceramic green sheet having a predeterminedthickness is formed by a reverse roll coater process, a doctor bladeprocess, or a like process.

Next, as shown in FIG. 5, a plurality of ceramic green sheets 21 a to 21f are formed from the above-prepared ceramic green sheet by blankingwith a die, laser machining, or like machining.

In the example of FIG. 5, rectangular windows Wd1 to Wd4 are formed inthe ceramic green sheets 21 b to 21 e, respectively. The windows Wd1 andWd4 have substantially the same shape, and the windows Wd2 and Wd3 havesubstantially the same shape. Each of the ceramic green sheets 21 a and21 f includes a portion that is formed into the thin-plate portion 12.Each of the ceramic green sheets 21 b and 21 e includes a portion thatis formed into the holding portion 13. Notably, the number of ceramicgreen sheets is given merely as an example. In the illustrated example,the ceramic green sheets 21 c and 21 d may be replaced with a singlegreen sheet having a predetermined thickness or with a plurality ofceramic green sheets to be laminated so as to obtain the predeterminedthickness or with a green sheet laminate having the predeterminedthickness.

Subsequently, as shown in FIG. 6, the ceramic green sheets 21 a to 21 fare laminated and compression-bonded to thereby form the ceramic greensheet laminate 22. Next, the ceramic green sheet laminate is fired tothereby form the ceramic laminate 23 shown in FIG. 7.

No particular limitations are imposed on the number and order ofcompression-bonding operations for forming the ceramic green sheetlaminate 22 (for monolithic lamination). In the case where a portion towhich pressure is not sufficiently transmitted by uniaxial applicationof pressure (application of pressure in a single direction) exists,desirably, compression bonding is repeated a plurality of times, orimpregnation with a pressure-transmitting substance is employed incompression bonding. Also, for example, the shape of the windows Wd1 toWd4 and the number and thickness of ceramic green sheets can bedetermined as appropriate according to the structure and function of thepiezoelectric/electrostrictive device 10 to be manufactured.

When the above compression bonding for monolithic lamination isperformed while heat is applied, a more reliable state of lamination isobtained. When a paste, a slurry, or the like that contains apredominant amount of a ceramic powder and a binder and serves as abonding aid layer is applied to ceramic green sheets by means of coatingor printing before the ceramic green sheets are compression-bonded, thestate of bonding at the interface between the ceramic green sheets canbe enhanced. In this case, preferably, the ceramic powder to be used asa bonding aid has a composition identical with or similar to a ceramicused in the ceramic green sheets 21 a to 21 f in view of the reliabilityof bonding. Furthermore, in the case where the ceramic green sheets 21 aand 21 f are thin, the use of a plastic film (particularly, apolyethylene terephthalate film coated with a silicone-base partingagent) is preferred in handling the ceramic green sheets 21 a and 21 f.When the windows Wd1 and Wd4 and the like are to be formed in relativelythin sheets, such as the ceramic green sheets 21 b and 21 e, each ofthese sheets may be attached to the above-mentioned plastic film beforea process for forming the windows Wd1 and Wd4 and the like is performed.

Next, as shown in FIG. 8, the piezoelectric/electrostrictive laminates24 are formed on the corresponding opposite sides of the ceramiclaminate 23; i.e., on the corresponding surfaces of the fired ceramicgreen sheets 21 a and 21 f. Examples of methods for forming thepiezoelectric/electrostrictive laminates 24 include thick-film formationprocesses, such as a screen printing process, a dipping process, acoating process, and an electrophoresis process; and thin-film formationprocesses, such as an ion beam process, a sputtering process, a vacuumdeposition process, an ion plating process, a chemical vapor deposition(CVD) process, and a plating process.

The use of such a film formation process in formation of thepiezoelectric/electrostrictive laminates 24 allows thepiezoelectric/electrostrictive laminates 24 and the thin-plate portions12 to be monolithically bonded (disposed), thereby securing reliabilityand reproducibility and facilitating integration.

In this case, more preferably, a thick-film formation process is usedfor forming the piezoelectric/electrostrictive laminates 24. Athick-film formation process allows, in film formation, the use of apaste, a slurry, a suspension, an emulsion, a sol, or the like thatcontains a predominant amount of piezoelectric ceramic particles orpowder having an average particle size of 0.01 μm to 5 μm, preferably0.05 μm to 3 μm. The piezoelectric/electrostrictive laminates 24obtained by firing the thus-formed films exhibit a goodpiezoelectric/electrostrictive characteristic.

An electrophoresis process has such an advantage that a film can beformed with high density and high shape accuracy. A screen printingprocess can simultaneously perform control of film thickness and patternformation and thus can simplify a manufacturing process.

An example method for forming the ceramic laminate 23 and thepiezoelectric/electrostrictive laminates 24 will be described in detail.First, the ceramic green sheet laminate 22 is monolithically fired at atemperature of 1,200° C. to 1,600° C., thereby yielding the ceramiclaminate 23 shown in FIG. 7. Subsequently, as shown in FIG. 3, theelectrodes 14 a 1 are printed on the corresponding opposite sides of theceramic laminate 23 at a predetermined position, followed by firing.Next, the piezoelectric/electrostrictive layers 14 b 1 are printed andfired. The electrodes 14 a 2 are printed on the correspondingpiezoelectric/electrostrictive layers 14 b 1, followed by firing. Suchan operation is repeated a predetermined number of times to thereby formthe piezoelectric/electrostrictive laminates 24. Subsequently, aterminal (not shown) for electrically connecting the electrodes 14 a 1,14 a 3, and 14 a 5 to a drive circuit, and a terminal (not shown) forelectrically connecting the electrodes 14 a 2 and 14 a 4 to the drivecircuit are printed and fired.

Alternatively, the piezoelectric/electrostrictive laminates 24 may beformed as follows. The bottom electrode 14 a 1 is printed and fired.Subsequently, the piezoelectric/electrostrictive layer 14 b 1 and theelectrode 14 a 2 are printed and are then simultaneously fired.Similarly, a process in which a single piezoelectric/electrostrictivelayer and a single electrode are printed and then simultaneously firedis repeated a predetermined number of times.

In this case, for example, the electrodes 14 a 1, 14 a 2, 14 a 3, and 14a 4 are formed from a material that contains a predominant amount ofplatinum (Pt); the piezoelectric/electrostrictive layers 14 b 1 to 14 b4 are formed from a material that contains a predominant amount of leadzirconate titanate (PZT); the electrode 14 a 5 is formed from gold (Au);and the terminals are formed from silver (Ag). In this manner, materialsare selected in such a manner that their firing temperature lowers inthe ascending order of lamination. As a result, at a certain firingstage, a material(s) that has been fired is free from re-sintering,thereby avoiding occurrence of a problem, such as the exfoliation orcohesion of an electrode material.

The selection of appropriate materials allows the members of thepiezoelectric/electrostrictive laminates 24 and the terminals to besequentially printed and then monolithically fired in a single firingoperation. Also, the piezoelectric/electrostrictive laminate 24 may beformed as follows: a firing temperature for the outermostpiezoelectric/electrostrictive layer 14 b 4 is set higher than that forthe piezoelectric/electrostrictive layers 14 b 1 to 14 b 3, so as tofinally bring the piezoelectric/electrostrictive layers 14 b 1 to 14 b 4into the same sintered state.

The members of the piezoelectric/electrostrictive laminates 24 and theterminals may be formed by a thin-film formation process, such as asputtering process or a vapor deposition process. In this case, heattreatment is not necessarily required.

The following simultaneous firing process may be employed. Thepiezoelectric/electrostrictive laminates 24 are formed on thecorresponding opposite sides of the ceramic green sheet laminate 22;i.e., on the corresponding surfaces of the ceramic green sheets 21 a and21 f. Subsequently, the ceramic green sheet laminate 22 and thepiezoelectric/electrostrictive laminates 24 are simultaneously fired.

In an example method for simultaneously firing thepiezoelectric/electrostrictive laminates 24 and the ceramic green sheetlaminate 22, precursors of the piezoelectric/electrostrictive laminates24 are formed by a tape formation process using a slurry material, or alike process; the precursors of the piezoelectric/electrostrictivelaminates 24 are laminated on the corresponding opposite sides of theceramic green sheet laminate 22 by thermo-compression bonding or thelike; and subsequently the precursors and the ceramic green sheetlaminate 22 are simultaneously fired. However, in this method, theelectrodes 14 a 1 must be formed beforehand on the correspondingopposite sides of the ceramic green sheet laminate 22 and/or on thecorresponding piezoelectric/electrostrictive laminates 24 by use of anyfilm formation process mentioned above.

In another method, the electrodes 14 a 1 to 14 a 5 and thepiezoelectric/electrostrictive layers 14 b 1 to 14 b 4, which arecomponent layers of the piezoelectric/electrostrictive laminates 24, arescreen-printed at least on those portions of the ceramic green sheetlaminate 22 which are finally formed into the corresponding thin-plateportions 12; and the component layers and the ceramic green sheetlaminate 22 are simultaneously fired.

A firing temperature for a component layer of thepiezoelectric/electrostrictive laminates 24 depends on the material ofthe component layer, but is generally 500° C. to 1,500° C. A preferredfiring temperature for the piezoelectric/electrostrictive layers 14 b 1to 14 b 4 is 1,000° C. to 1,400° C. In this case, preferably, in orderto control the composition of the piezoelectric/electrostrictive layers14 b 1 to 14 b 4, sintering is performed in such a state thatevaporation of the material of the piezoelectric/electrostrictive layers14 b 1 to 14 b 4 is controlled (for example, in the presence of anevaporation source). In the case where thepiezoelectric/electrostrictive layers 14 b 1 to 14 b 4 and the ceramicgreen sheet laminate 22 are simultaneously fired, their firingconditions must be compatible with each other. Thepiezoelectric/electrostrictive laminates 24 are not necessarily formedon the corresponding opposite sides of the ceramic laminate 23 or theceramic green sheet laminate 22, but may be formed only on a single sideof the ceramic laminate 23 or the ceramic green sheet laminate 22.

Next, unnecessary portions are cut away from the ceramic laminate 23 onwhich the piezoelectric/electrostrictive laminates 24 are formed asdescribed above. Specifically, the ceramic laminate 23 is cut alongcutting lines (broken lines) C1 to C4 shown in FIG. 9. Cutting can beperformed by mechanical machining, such as wire sawing or dicing, aswell as laser machining, such as YAG laser machining or excimer lasermachining, or electron beam machining.

Among the above cutting methods, dicing is undesirable for the followingreason. Cutting the ceramic laminate 23 and thepiezoelectric/electrostrictive laminates 24 along the cutting lines(broken lines) C3 and C4 of FIG. 9 includes cutting of the components ofthe piezoelectric/electrostrictive laminates 24; i.e., cutting ofpiezoelectric/electrostrictive layers which are relatively low instrength and fragile, and a metal which is ductile. Thus, dicing, whichimposes a large machining load on an object to be cut (hereinafter, a“monolithic body including the ceramic laminate 23 and thepiezoelectric/electrostrictive laminate 24,” which partially constitutesthe piezoelectric/electrostrictive device 10, is also referred to as an“object to be cut”), is undesirable. Machining of another type whosemachining load to be imposed on an object to be cut is small isdesirable. Particularly, wire sawing is suited for such cutting, sincewire sawing is suited for simultaneously forming a plurality ofpiezoelectric/electrostrictive devices 10 by means of simultaneouscutting and is small in machining load.

In this case, the above-mentioned cutting (wire sawing) is performed asfollows. A wire saw WS, which serves as a wire member, is caused toadvance (move) in a direction parallel to a layer plane along thecutting lines C3 and C4 while the wire saw WS is caused to reciprocatein a direction substantially parallel to the direction of lamination ofthe laminar electrodes 14 a 1 to 14 a 5 and thepiezoelectric/electrostrictive layers 14 b 1 to 14 b 4 of thepiezoelectric/electrostrictive laminates 24 as represented by the arrowAR1 of FIG. 9; in other words, in a direction substantiallyperpendicular to the layer planes of the electrodes 14 a 1 to 14 a 5 andthe piezoelectric/electrostrictive layers 14 b 1 to 14 b 4 (in adirection substantially perpendicular to boundary surfaces betweenlaminar electrodes and piezoelectric/electrostrictive layers; therefore,in a direction substantially perpendicular to planes of the firedceramic green sheets 21 a and 21 f) and is held substantially parallelto the direction of lamination.

Desirably, wire sawing is performed in such a manner that the holecomposed of the window d1 and other windows is filled with a filler,such as wax or resin, so as to prevent vibration of the thin-plateportions (portions corresponding to the ceramic green sheets 21 a and 21f). After wire sawing, the filler may be removed by dissolution with anappropriate solvent or may be burned out. Desirably, before wire sawingis performed, an organic resin, or a paste or the like composed of anorganic resin and a ceramic is applied to the surfaces of the laminates24, which are formed into the piezoelectric/electrostrictive elements14, followed by drying and curing to thereby form a protective film(protective layer). The thickness of the protective film is desirably 1μm to 500 μm, more desirably 20 μm to 100 μm. The protective film can beformed by printing, spraying, or the like. Desirably, the thickness ofthe outermost electrode of the piezoelectric/electrostrictive element isincreased so that the electrode layer serves as the protective layer tocope with wire sawing.

The above-mentioned object to be cut is not directly mounted to awire-sawing stage. Generally, the object to be cut is bonded to a jig byuse of wax, an adhesive, or the like, and the jig is mounted to thewire-sawing stage. Desirably, a cut base (a member to be cut togetherwith the object to be cut), such as a plate of glass or silicon wafer, aplate of an organic resin (PET, PC, PE, PP, or the like), or film or alike thin plate of such an organic resin, is interposed between the jigand the object to be cut. In this case, desirably, an adhesive used forbonding the object to be cut and the cut base, and an adhesive used forbonding the cut base and the jig differ in mutual solubility withrespect to respectively predetermined solvents.

Selection of such adhesives can prevent a solvent used for separatingthe cut base and the jig from affecting a bond between the cut base anda cut object. Thus, after the cut base and the jig are separated fromeach other, the cut object can be handled while being bonded to the cutbase. For example, when abrasive grains which adhere, during wiresawing, to the object to be cut are to be cleaned off, an operation ofsetting (placing) the cut object in a cleaning jig is facilitated byemployment of the following practice: the cut object bonded to the cutbase is placed in the cleaning jig at a predetermined position and thencleaned, and subsequently the cut base and the cut object are separatedfrom each other in the cleaning jig.

Desirably, in order to stabilize the reciprocating motion of a wire,wire sawing is performed as follows. As shown in FIG. 32, at least apair of guides GD are disposed in such a manner that objects HS to becut are held between the guides GD. First, a wire WS cuts into theguides GD, whereby the reciprocating motion of the wire WS isstabilized. Subsequently, the wire WS begins to cut the objects HS to becut. Desirably, a material for the guide GD is a ceramic, such asalumina, zirconia, ferrite, or glass, an aforementioned metallicmaterial, carbon, graphite, monocrystalline silicon, or the like.Needless to say, the height hg of the guide GD is slightly greater thanthe height hs of the object HS to be cut. The differential height(hg−hs) between the guide GD and the object HS to be cut is desirablyone time the diameter of the wire or more, more desirably three times ormore. However, since the differential height between the guide and theobject to be cut must be reduced in view of machining, more desirably,the differential height is 10 times the wire diameter or less.

In order to enhance ejection (taking out) of abrasive grains, thethickness of the guide as measured in the direction of the reciprocatingmovement of the wire is desirably small; specifically, 5 mm or less,more desirably 2 mm or less. Desirably, the guide has a small thicknessas measured in the direction of the reciprocating movement of the wireand high rigidity and is easy to cut (highly easy to grind) by abrasivegrains. Specifically, use of carbon is desirable. Alternatively,selection may be made from among iron, any other metal, SUS, glass,alumina, and zirconia in that order while considering machinability withrespect to the object to be cut.

Desirably, when the wire is moved away from the cut object aftercompletion of wire sawing, the wire is caused to continue reciprocatingso as to maintain a state of ejection of abrasive grains as duringcutting. Also, the wire is preferably moved away from the cut objectafter the reciprocating speed is increased from that during cutting.This yields the effect of smoothening the machined lateral end surfacesof the cut object by means of rubbing with the wire and abrasive grains.An abrasive material (grains) for use with the wire saw is appropriatelyselected from SiC, Al₂O₃, ZrO₂, diamond, and the like and has an averagegrain size of 1 μm to 30 μm, desirably 1 μm to 5 μm.

During wire sawing, the wire (wire saw) WS has a reciprocating speed (inthe reciprocating direction represented by the arrow AR1 of FIG. 9) of10 m/min to 1,500 m/min, desirably 100 m/min to 600 m/min. The feed rateof the wire (in a direction perpendicular to the reciprocating directionrepresented by the arrow AR1 of FIG. 9; i.e., in a cutting advancementdirection) is 0.5 mm/min, desirably 0.1 mm/min or less. Desirably, thetension of the wire WS is 1 N to 20 N.

Wire sawing may be performed as follows: instead of feeding the wire WSat a constant rate after the wire WS comes into contact with the objectHS to be cut and begins to cut the object HS, at the beginning ofmachining of the object HS, an operation of temporarily suspending thefeed of the wire WS or reversing the feed, and resuming the feed isrepeated, so that machining in the direction of feed proceeds gradually.In the case where feed is temporarily suspended, the machining in thedirection of feed is desirably performed by repeating an operation offeeding the wire WS from the machining start point by a quantity equalto or greater than an average grain size of abrasive material and equalto or less than ½, preferably ¼, of the diameter of the wire WS, andthen suspending the feed of the wire WS. In the case where feed isreversed, the feed of the wire WS is reversed by a quantity equal to orgreater than the average grain size of abrasive material, preferablyfive times the average grain size. In this case, the reverse rate may begreater than the feed rate. These practices can reduce a machining loadimposed on a surface to be machined and can improve the finish of themachined surface.

During wire sawing, abrasive grains or foreign matter, such as adhesive,adheres to the object to be cut. Such an adhering substance is desirablyremoved from the cut object by means of cleaning. At that time, ifforeign matter is allowed to evaporate and solidify, removal of foreignmatter becomes difficult. Therefore, desirably, foreign matter iscleaned off while the foreign matter is caused not to evaporate and dry.When such cleaning is to be performed, a solvent that is used forsuspending abrasive grains in order to spray the abrasive grains on theobject to be cut during wiring sawing is used at an initial stage of thecleaning.

In contrast to cutting along the cutting lines C3 and C4, in which acomplex including ceramics, electrodes, andpiezoelectric/electrostrictive layers which differ in mechanicalcharacteristics (different physical properties in relation to cutting)is cut, cutting a portion of ceramics of uniform or similar mechanicalcharacteristics can be performed by wire sawing or any other machiningmethod. For example, preferably, dicing is employed for cutting aportion to be formed into the holding portions 13, and a portion to beformed into the stationary portion 11, in a direction perpendicular tothe cutting lines C3 and C4. By the above-described method, thepiezoelectric/electrostrictive device 10 of FIG. 1 is manufactured.

According to the above-describe manufacturing method, the wire saw WS iscaused to advance in a direction parallel to the layer planes of thepiezoelectric/electrostrictive laminates 24 and in a plane perpendicularto the layer planes while the wire saw WS is caused to reciprocate inthe direction of lamination of the piezoelectric/electrostrictivelaminates 24 and is held parallel to the direction of lamination,whereby the piezoelectric/electrostrictive laminates 24 are cut tothereby yield the final shape of the piezoelectric/electrostrictiveelement 14. As shown in FIG. 10, a front view of the lateral end surface(cut surface) of the piezoelectric/electrostrictive element 14 and thethin-plate portion 12, and in FIG. 11, a sectional view taken along line2-2 of FIG. 10 and showing the piezoelectric/electrostrictive element 14and the thin-plate portion 12, a portion of, for example, the electrode14 a 2 which portion forms the lateral end surface extends onto thelateral end surfaces of the piezoelectric/electrostrictive layers 14 b 1and 14 b 2 between which the electrode 14 a 2 is sandwiched, in such amanner as to partially cover the lateral end surfaces of thepiezoelectric/electrostrictive layers 14 b 1 and 14 b 2. That is, aportion of each of the electrodes 14 a 1 to 14 a 5 of thepiezoelectric/electrostrictive element 14, which portion forms thecorresponding lateral end surface, extends onto the lateral end surfacesof the piezoelectric/electrostrictive layers between which the electrodeis sandwiched, in such a manner as to partially cover the lateral endsurfaces of the piezoelectric/electrostrictive layers.

As a result, as shown in FIG. 12, an enlarged view of FIG. 11, “on thelateral end surface of the piezoelectric/electrostrictive element 14,”the length L2 of “the lateral end surface of the electrode 14 an (n: 1to 5) as measured in the direction of lamination of thepiezoelectric/electrostrictive layers 14 bn and the electrode 14 an” issmaller than five times the length L1 of the electrode as measured inthe direction of lamination and on the imaginary plane HPL defined bythe lateral end surfaces of the piezoelectric/electrostrictive layers 14bn and 14 bn-1. Accordingly, on the lateral end surface of thepiezoelectric/electrostrictive element 14, the distance between adjacentelectrodes is increased, thereby reducing the susceptibility of adjacentelectrodes to short circuit in the course of manufacture or use.

Also, the piezoelectric/electrostrictive device 10 is such that a ratioof L3/L1 satisfies 0<L3/L1<2 (i.e., L3/L1 is greater than 0 and smallerthan 2), where L3 is the length of the longer of parts of alateral-end-surface-forming portion of each electrode 14 an whichportion forms the corresponding lateral end surface of the electrode,the parts of the portion covering the corresponding lateral end surfacesof the piezoelectric/electrostrictive layers 14 bn and 14 bn-1 betweenwhich the electrode 14 an is sandwiched, the length being measured inthe direction of lamination of the piezoelectric/electrostrictive layersand the electrode; and L1 is the thickness, as measured in the directionof lamination, of the lateral-end-surface-forming portion of theelectrode after removal of the parts covering the corresponding lateralend surfaces of the piezoelectric/electrostrictive layers from thelateral-end-surface-forming portion of the electrode.

The piezoelectric/electrostrictive device 10 in which the relation0<L3/L1<2 is satisfied is highly unsusceptible to a failure to exhibitsufficient insulating performance at the stage of completion ofmanufacture thereof and is highly unlikely to impair its insulatingperformance in the course of use. Additionally, when voltage is appliedto the electrodes, electric field intensity as measured on the lateralend surfaces of the piezoelectric/electrostrictive layers becomes higherthan internally measured electric field intensity, so that compressionstress can be effectively generated on the lateral end surfaces of thepiezoelectric/electrostrictive layers. As a result, the strength of thepiezoelectric/electrostrictive device 10 can be enhanced.

In a piezoelectric/electrostrictive device manufactured by a method thatdoes not comply with the present invention, as shown in FIG. 13equivalent to FIG. 12, in some cases, “on the lateral end surface of thepiezoelectric/electrostrictive element 14,” the length L20 of a “portionof the electrode 14 an (n: 1 to 5) forming the lateral end surface asmeasured in the direction of lamination of thepiezoelectric/electrostrictive layers 14 bn and the electrode 14 an”becomes greater than five times the length L10 of the electrode asmeasured in the direction of lamination and on the imaginary plane HPLdefined by the lateral end surfaces of thepiezoelectric/electrostrictive layers 14 bn and 14 bn-1, indicating apossible failure to provide sufficient reliability.

Next, a second method for manufacturing thepiezoelectric/electrostrictive device 10 according to the presentinvention will be described. First, a binder, a solvent, a dispersant, aplasticizer, and the like are mixed with a ceramic powder of zirconia orthe like, thereby preparing a slurry. The slurry is defoamed. By use ofthe defoamed slurry, a rectangular ceramic green sheet having apredetermined thickness is formed by a reverse roll coater process, adoctor blade process, or a like process.

Next, as shown in FIG. 14, a plurality of ceramic green sheets 31 a to31 f are formed from the above-prepared ceramic green sheet by blankingwith a die, laser machining, or like machining. Particularly, blankingwith a die is most preferred in terms of a formed shape, the conditionof a machined surface, and a machining speed (machining quantity).

In the example shown in FIG. 14, as in the case of the ceramic greensheets 21 b to 21 e appearing in the previously described firstmanufacturing method, the rectangular windows Wd1 to Wd4 are formed inceramic green sheets 31 b to 31 e, respectively. The windows Wd1 and Wd4have substantially the same shape, and the windows Wd2 and Wd3 havesubstantially the same shape.

Windows We1 to We6 of substantially the same shape are formed in theceramic green sheets 31 a to 31 f, respectively. Windows Wf1 to Wf4 ofsubstantially the same shape are formed in the ceramic green sheets 31a, 31 b, 31 e, and 31 f, respectively. Each of the ceramic green sheets31 a and 31 f includes a portion that is formed into the thin-plateportion 12. Each of the ceramic green sheets 31 b and 31 e includes aportion that is formed into the holding portion 13. Also, in this case,the number of ceramic green sheets is given merely as an example. In theillustrated example, each of the ceramic green sheets 31 c and 31 d isin a state in which a plurality of ceramic green sheets are laminated.

Subsequently, as shown in FIG. 15, the ceramic green sheets 31 a to 31 fare laminated and compression-bonded to thereby form a ceramic greensheet laminate 32. Next, the ceramic green sheet laminate 32 is fired tothereby form a ceramic laminate 33 shown in FIG. 16.

Next, as in the case of the previously describedpiezoelectric/electrostrictive laminates 24, as shown in FIG. 17, thepiezoelectric/electrostrictive laminates 34 are formed on thecorresponding opposite sides of the ceramic laminate 33; i.e., on thecorresponding surfaces of the fired ceramic green sheets 31 a and 31 f.

Next, unnecessary portions are cut away from the ceramic laminate 33 onwhich the piezoelectric/electrostrictive laminates 34 are formed.Specifically, the ceramic laminate 33 on which thepiezoelectric/electrostrictive laminates 34 are formed is cut alongcutting lines (broken lines) C10 to C40 shown in FIG. 18. Cutting can beperformed by mechanical machining, such as wire sawing or dicing, aswell as laser machining, such as YAG laser machining or excimer lasermachining, or electron beam machining.

Among the above cutting methods, dicing is undesirable for the followingreason. Cutting the ceramic laminate 33 and thepiezoelectric/electrostrictive laminates 34 along the cutting lines(broken lines) C30 and C40 of FIG. 18 includes cutting thepiezoelectric/electrostrictive laminates 34, whose strength is low.Thus, dicing, which imposes a large machining load on an object to becut, is undesirable. Machining of another type whose machining load tobe imposed on an object to be cut is small is desirable. Particularly,wire sawing is suited for such cutting, since wire sawing is suited forsimultaneously forming a plurality of piezoelectric/electrostrictivedevices 10 by means of simultaneous cutting and is small in machiningload.

Wire sawing along the cutting lines C30 and C40 is performed in a mannersimilar to that of the first manufacturing method. Specifically, a wiresaw WS is caused to advance along the cutting lines C30 and C40 whilethe wire saw WS is caused to reciprocate in a direction substantiallyparallel to the direction of lamination of thepiezoelectric/electrostrictive laminates 34 as represented by the arrowAR1 of FIG. 18 and is held substantially parallel to the direction oflamination. As a result, the piezoelectric/electrostrictive device 10 iscompleted.

As in the case of the first manufacturing method, the secondmanufacturing method also uses the wire saw WS to cut thepiezoelectric/electrostrictive laminate 34. Thus, as shown in FIGS. 11and 12, a portion of each of the electrodes 14 a 1 to 14 a 5 of thepiezoelectric/electrostrictive element 14, which portion forms thecorresponding lateral end surface, extends onto the lateral end surfacesof the piezoelectric/electrostrictive layers 14 b 1 and 14 b 2, 14 b 2and 14 b 3, or 14 b 3 and 14 b 4 between which the electrode issandwiched, in such a manner as to partially cover the lateral endsurfaces of the piezoelectric/electrostrictive layers. The lengths(thicknesses) L1 and L2 of each electrode satisfy the conditionsspecified in the first manufacturing method. As a result, on the lateralend surface of the piezoelectric/electrostrictive element 14, thedistance between adjacent electrodes is increased, thereby reducing thesusceptibility of adjacent electrodes to short circuit.

In the second manufacturing method, the overall length of thepiezoelectric/electrostrictive device (length between the end of theholding portion 13 and the end of the stationary portion 11) isdetermined, not by cutting the fired body (ceramic laminate 33), but bymachining the green sheets (by forming the windows We1 to We6 and thewindows Wf1 to Wf4). As compared with the case of cutting the thickfired body, the overall length can be uniformly determined amongproducts (the overall length can be accurately determined).

Next will be described an example of ceramic green sheets to be used inactually manufacturing a plurality of piezoelectric/electrostrictivedevices by use of the above-described second manufacturing method. FIG.19 is an enlarged fragmentary front view of a ceramic green sheet 41corresponding to the ceramic green sheet 31 b shown in FIG. 14(accordingly, also corresponding to the ceramic green sheet 31 e). InFIG. 19, the broken lines correspond to the cutting lines C10 to C40 forthe aforementioned ceramic laminate which is yielded as a result offiring. As is apparent from FIG. 19, when the mutually adjacent windowsWf2, Wd1, and We2 are taken as a single group of cavities, a singlepiezoelectric/electrostrictive device 10 per group of cavities ismanufactured from the ceramic green sheet 41.

FIG. 19 shows the ceramic green sheet 41 corresponding to the ceramicgreen sheets 31 b and 31 e shown in FIG. 14, however, needless to say,ceramic green sheets corresponding to the ceramic green sheets 31 a, 31c, 31 d, and 31 f shown in FIG. 14 are prepared; the ceramic greensheets are laminated into a ceramic green sheet laminate that includes aplurality of ceramic green sheet laminates 32; the ceramic green sheetlaminate is fired into a ceramic laminate that includes a plurality ofceramic laminates 33; and the ceramic laminate is used to manufacture aplurality of piezoelectric/electrostrictive devices (the same conventionalso applies to the following descriptions of FIGS. 20 and 21).

FIG. 20 is an enlarged fragmentary front view of another ceramic greensheet 42 corresponding to the ceramic green sheet 31 b shown in FIG. 14(accordingly, also corresponding to the ceramic green sheet 31 e). InFIG. 20, the broken lines correspond to the cutting lines C10 to C40 forthe aforementioned ceramic laminate which is yielded as a result offiring. In the present example, cutting lines C50 and C60 are added forthe ceramic laminate. A ceramic green sheet laminate that includes theceramic green sheets 42 is fired into a ceramic laminate. The ceramiclaminate that includes the ceramic laminates 33 and thepiezoelectric/electrostrictive laminates 34 is cut along the cuttinglines C50 and C60. As is apparent from FIG. 20, when the mutuallyadjacent windows Wf2, Wd1, and We2 are taken as a single group ofcavities, a number of (three in the illustrated example)piezoelectric/electrostrictive devices 10 per group of cavities aremanufactured from the ceramic green sheet 42.

FIG. 21 is an enlarged fragmentary front view of still another ceramicgreen sheet 43 corresponding to the ceramic green sheet 31 b shown inFIG. 14 (accordingly, also corresponding to the ceramic green sheet 31e).

In contrast to the above-mentioned ceramic green sheet 42, the ceramicgreen sheet 43 is such that the windows Wf2 and We2 of the ceramic greensheet 41 or 42 are integrated into a single window Wg1 and such thatcutting is performed along a cutting line C70, which is an integratedcutting line of the aforementioned cutting lines C10 and C20, and alongthe cutting lines C30 to C60. Accordingly, when the window Wd1 and apair of windows Wg1 located on opposite sides of the window Wd1 aretaken as a single group of cavities, a number of (three in theillustrated example) piezoelectric/electrostrictive devices 10 per groupof cavities are manufactured from the ceramic green sheet 43.

The ceramic green sheet 43 requires formation of only a single windowWg1, which is an integrated window of the windows Wf2 and We2 of theceramic green sheet 41 or 42, instead of formation of the windows Wf2and We2, thereby simplifying a preparation process (blanking process)for the ceramic green sheet 43. Also, the number of products availablefrom the same sheet area can be increased.

Referring to FIGS. 19 and 20, the following cutting sequence (foryielding devices) is desirable. First, cutting is performed along thecutting lines C10 and C20, which longitudinally extend in the windowsthat determine the overall device length. Next, portions (substantiallyprismatic cut objects HS) remaining after removal of portions irrelevantto products (portions each sandwiched between the windows Wfn (Wf2) andWen (We2) that are adjacent to each other without having the window Wdn(Wd1) therebetween (portions each sandwiched between the cutting linesC10 and C20 and not including the window Wd1)) are rearranged, forexample, as shown in FIG. 32. Subsequently, wire sawing is performedalong the cutting lines C30, C40, C50, and C60.

In the case of cutting shown in FIG. 21, cutting may be performed in asequence similar to that for cutting shown in FIGS. 19 and 20 or may beperformed in the reverse sequence. Specifically, first, wire sawing isperformed along the cutting lines C30, C40, C50, and C60. Subsequently,cutting for determining the overall device length is performed along thecutting lines C70.

Supplementary description will next be given with respect to theabove-described first and second manufacturing methods. Preferably,after cutting (cutting-off) is performed along the cutting lines C3 andC4 shown in FIG. 9 (along the cutting lines C30 and C40 shown in FIG.18), the piezoelectric/electrostrictive laminates 24 (34) and theceramic laminate 23 (33) are subjected to heat treatment at 300° C. to800° C. The heat treatment can eliminate a defect, such as a microcrack,which is likely to occur in the piezoelectric/electrostrictive device 10as a result of cutting, thereby enhancing reliability. Furthermore,preferably, after the heat treatment, the piezoelectric/electrostrictivelaminates 24 (34) and the ceramic laminate 23 (33) are allowed to standat a temperature of about 80° C. for about 10 hours so as to be aged.The aging treatment can alleviate various stresses and the like that aregenerated in the piezoelectric/electrostrictive device 10 in the courseof manufacture.

The above-described piezoelectric/electrostrictive device according tothe present invention can be used as active elements, such as varioustransducers, various actuators, frequency-domain functional components(filters), transformers, vibrators and resonators for use incommunication and power applications, oscillators, and discriminators;and also as sensor elements for use in various sensors, such asultrasonic sensors, acceleration sensors, angular-velocity sensors,impact sensors, and mass sensors. Also, thepiezoelectric/electrostrictive device can be used as various actuatorsfor use in mechanisms for displacement, positioning adjustment, or angleadjustment of various precision components in optical equipment,precision equipment, and like equipment.

While the present invention has been described with reference to anembodiment of the piezoelectric/electrostrictive device and anembodiment of the method for manufacturing the same, the presentinvention is not limited thereto, but may be modified as appropriatewithout departing from the scope of the invention. For example, thepiezoelectric/electrostrictive element 14 of the above-describedembodiment includes a plurality of electrodes 14 a 1 to 14 a 5 and aplurality of piezoelectric/electrostrictive layers 14 b 1 to 14 b 4.However, a piezoelectric/electrostrictive element including a pair ofelectrodes and a single piezoelectric/electrostrictive layer sandwichedbetween the paired electrodes can be employed in thepiezoelectric/electrostrictive device of the present invention; and themethod for manufacturing a piezoelectric/electrostrictive deviceaccording to the present invention can be applied to manufacture of thepiezoelectric/electrostrictive device.

Specifically, the piezoelectric/electrostrictive device includes thestationary portion 11 of the above-described embodiment; the thin-plateportion 12 supported by the stationary portion 11; and apiezoelectric/electrostrictive element including a laminar firstelectrode (corresponding to the electrode 14 a 1 of the above-describedembodiment) formed on a plane of the thin-plate portion 12, apiezoelectric/electrostrictive layer (corresponding to thepiezoelectric/electrostrictive layer 14 b 1 of the above-describedembodiment) formed on the first electrode, and a laminar secondelectrode (corresponding to the electrode 14 a 2 of the above-describedembodiment) formed on the piezoelectric/electrostrictive layer. In thepiezoelectric/electrostrictive device, a portion of the first electrodewhich portion forms a lateral end surface of the first electrode extendsonto a lateral end surface of the thin-plate portion 12 and onto alateral end surface of the piezoelectric/electrostrictive layer, in sucha manner as to partially cover the lateral end surface of the thin-plateportion 12 and the lateral end surface of thepiezoelectric/electrostrictive layer.

The piezoelectric/electrostrictive device is manufactured by a methodthat includes a step of forming a laminate adapted to form thepiezoelectric/electrostrictive element, on a plane of a thin-platemember adapted to form the thin-plate portion 12 and a step of formingthe thin-plate portion and the piezoelectric/electrostrictive element byadvancing a wire member reciprocating in a direction substantiallyparallel to the direction of lamination of the laminate while holdingthe wire member substantially parallel to the direction of lamination,so as to cut the thin-plate member and the laminate.

In the case where the stationary portion 11, the thin-plate portions 12,and the holding portions 13 are formed from a metal, in place of theceramic laminate 23 shown in FIG. 7 or the ceramic laminate 33 shown inFIG. 16, a metal structure having the same shape as that of the ceramiclaminates may be formed by casting. Alternatively, metal sheets whoseshapes are identical with those of the ceramic green sheets shown inFIG. 5 or FIG. 14 may be prepared and laminated together by a claddingprocess to thereby form a metal structure having the same shape as thatof the ceramic laminates 23 and 33.

In the piezoelectric/electrostrictive device 10 of the above-describedembodiment, an object is held between the paired holding portions 13.However, as shown in FIG. 22, a spacer 13 a may be held between thepaired holding portions 13 via adhesives 13 b. Furthermore, as shown inFIG. 23, an object may be held on lateral end surfaces (on lowersurfaces in FIG. 23) of the holding portions of thepiezoelectric/electrostrictive device according to the above-describedembodiment by means of bonding or the like.

Furthermore, the structure shown in FIG. 24 may be employed.Specifically, a central portion of the stationary portion 11 in theabove-described embodiment is cut off to thereby form a pair ofstationary portions 11 a, so that the stationary portions 11 a supportthe corresponding thin-plate portions 12. Tip end portions of the pairedthin-plate portions 12 are integrally connected to thereby form aholding portion 13 a.

1. A method for manufacturing a piezoelectric/electrostrictive deviceincluding a thin-plate portion, a stationary portion supporting thethin-plate portion, and a piezoelectric/electrostrictive elementincluding a plurality of electrodes and a plurality ofpiezoelectric/electrostrictive layers arranged alternatingly in layers,comprising: a step of forming a piezoelectric/electrostrictive laminateby alternatingly laminating laminar electrodes andpiezoelectric/electrostrictive layers on a plane of a thin-plate memberadapted to form the thin-plate portion; and a step of forming thethin-plate portion and the piezoelectric/electrostrictive element byadvancing a wire member reciprocating in a direction substantiallyparallel to the direction of lamination of thepiezoelectric/electrostrictive laminate while holding the wire membersubstantially parallel to the direction of lamination, so as to cut thethin-plate member and the piezoelectric/electrostrictive laminate.
 2. Amethod for manufacturing a piezoelectric/electrostrictive deviceincluding a thin-plate portion, a stationary portion supporting thethin-plate portion, and a piezoelectric/electrostrictive elementincluding a plurality of electrodes and a plurality ofpiezoelectric/electrostrictive layers arranged alternatingly in layers,comprising: a step of forming a ceramic laminate by firing a ceramicgreen sheet laminate including a ceramic green sheet adapted to form thestationary portion, and a ceramic green sheet adapted to form thethin-plate portion; a step of forming a piezoelectric/electrostrictivelaminate at least on a surface of a portion of the ceramic laminatewhich is formed into the thin-plate portion, thepiezoelectric/electrostrictive laminate including laminar electrodes andpiezoelectric/electrostrictive layers arranged alternatingly in layers;and a step of forming the thin-plate portion and thepiezoelectric/electrostrictive element by advancing a wire memberreciprocating in a direction substantially parallel to the direction oflamination of the piezoelectric/electrostrictive laminate while holdingthe wire member substantially parallel to the direction of lamination,so as to cut the portion of the ceramic laminate which is formed intothe thin-plate portion, and the piezoelectric/electrostrictive laminate.3. A method for manufacturing a piezoelectric/electrostrictive deviceincluding a thin-plate portion and a piezoelectric/electrostrictiveelement including a laminar first electrode formed on a plane of thethin-plate portion, a piezoelectric/electrostrictive layer formed on thefirst electrode, and a laminar second electrode formed on thepiezoelectric/electrostrictive layer, comprising: a step of forming alaminate adapted to form the piezoelectric/electrostrictive element, ona plane of a thin-plate member adapted to form the thin-plate portion;and a step of forming the thin-plate portion and thepiezoelectric/electrostrictive element by advancing a wire memberreciprocating in a direction substantially parallel to the direction oflamination of the laminate while holding the wire member substantiallyparallel to the direction of lamination, so as to cut the thin-platemember and the laminate.